This research is an interdisciplinary effort directed to the development of automated, feedback controlled, drug administration devices which function to continously monitor a drug's effect(s), process the data in real time, and control a servopump which meters out the drug in response to the patient's momentary needs. This fully automated approach is most feasible for short acting drugs, particularly those used during intensive care. The present request is for support of the further preliminary animal experimentation necessary to construct a device suitable for human, clinical application. Specifically, two rapid-acting hypotensive drugs will be studied: trimethaphan camsylate (arfonad), with which work has already been initiated and proven feasible, and sodium nitroprusside, which is a lesser used, but promising drug. These studies will be extended in future work to anesthetics (already clinically proven in feedback systems and now also being studied by us), antiarrhythmic drugs, skeletal muscle relaxants, and coronary vasodilators. Good control of blood pressure in normotensive rabbits using arfonad has been accomplished in our laboratory. We will continue with arfonad using dogs and extend work to include sodium nitroprusside; hypertensive and normotensive animal models will be studied. Experiments will be designed to establish the best type of control schemes and controller settings which optimally function in rapidly attaining and maintaining blood pressure at a desired level. The results will be interpreted with regard to applications in clinical testing of the technique in subsequent human studies. The hardward to be developed will consist of a portable electronic controller/computer to be interfaced with a blood pressure transducer and a servopump which intravenously administers the drug. The device will be designed for human use in the treatment of hypertensive emergencies and to accomplish controlled reductions in blood pressure over prolonged periods of time as may be desirable during surgery and in certain treatments of hypertension. Our very preliminary results indicate that these objectives are feasible to achieve.